One Identity Management Console for Unix is a web-based console that delivers a consolidated view and centralized point of management for local Unix users and groups
The QAC Schema consists in an ADUC container with the following path
<domain>\Program Data\Quest Software\Authentication Services\{786E0064-A470-46B9-83FB-C7539C9FA27C}\Schema
Inside this path, there are the following subcontainers
Gecos
GroupGidNumber
GroupName
HomeDirectory
LoginName
LoginShell
UidNumber
UserEmailAddress
UserGidNumber
UserMobileNumber
If you have additional containers on this list, they will prevent MCU to operate properly and they must be deleted.